The research proposed utilizes a novel assay for proteins from eukaryotic cells that can catalyze the initiation of the synthesis of DNA chains on single-stranded regions of template DNA. Such proteins are being sought from yeast cells. Their mechanisms of action and specificities for DNA templates will be examined to define the different pathways for the initiation of the sysnthesis of DNA chains. Our goal is to understand the biochemistry of the initiation of DNA synthesis in simple eukaryotes so as to understand its control.